The calorimetric determination of fluorescence quantum yield

Abstract

Fluorescence quantum yields of aromatic amino acids and those derivatives are determined by measuring thermal energies which are produced by nonradiative deactivation of excited molecules. The fluorescence quantum yields of ethanol solution of DNS-Trp, DNS-Gly, and Trp excited at 360 nm, 360 nm, and 280 nm, are 0.54, 0.50, and 0.10, respectively. Spectroscopically determined values of fluorescence yields of DNS-Trp and DNS-Gly are 0.53 and 0.48, respectively. These values which are determined by two methods coincide satisfactorily. The present method can be used as a new method for quantum yield which is substantially different from ordinary spectroscopic method. We suggest a possibility of opto-calorimetric analysis of absorptive and non-fluorescent compounds. Especially, for a long wavelength emission which can not be detected by a photomultiplier, the present method gets advantage over the spectroscopic method. The experimental system is very simple, consisting of fluoro-photometer (Hitachi 204 S) with some optional devices, and its measurements are also simple. © 1982, The Japan Society for Analytical Chemistry. All rights reserved.